Manufacture of calcium hypochlorite



Patented May 21, '1929.

TIES

N. Y A CORPORATION QF --VIRGINIA.

PATENT OFFICE.

No Drawing.

This invention relates to improvements in the production of calcium hypochlorite products. In the manufacture of calcium hypochlorite products, it is usually desirable to make products that are free from calcium chloride or contain but a minimum ofcalcium chloride for several reasons. In particu-' lar, calcium chloride is very hygroscopic and makes the products difficult to dry when present in substantial amount, and this same property of calcium chloride also tends to make the product unstable when itcontains calcium chloride in substantial amount. The present invention provides a method of freeing calcium hypochlorite products from such calcium chloride as they may contain.

According to the present invention, the calcium hypochlorite product containin calcium chloride is treated with sodium \ypochlorite. The sodium hyprochlorite reacts with calcium chloride present to convert it to calcium hypochlorite with the formation of sodium chloride. Sodium chloride, unlike calcium chloride, apparently does not adversely affect the stability of calcium hypochlorite, and the calcium hypochlorite formed in the treatment adds to the calcium hypochlorite content of the product. Any tendency to form difiicultly soluble basic hypochlorite is also avoided by using sodium hypochlorite, or other alkali hypochlorite.

The process of the invention is applicable to dry calcium hypochlorite products, or to slurries, or to filter or press cakes, or the containing calcium hypochlorite and calcium chloride. The treatment is carried out in the presence of suflicient water to enable thorough agitation and mixture of the calcium hypochlorite product with added alkali hypochlorite. With a dry product all of the The alkali hypochlorite may be used as such hypochlorite, 7.5% of like, 1

- Application filed August 4, 1926. Serial No. 127,116.

or in solution in carryin The alkali hypochlorite, or-example, may be added dissolved in thewater, or part of the Water, adequate agitation. As an example,.a solution containing sodium hypochlorite may be prepared by chlorinating a solution of pounds of caustic-soda dissolved in 65.3 pounds of water until not more than about 6% of the caustic soda added remains unchlorinated. It is then advantageous to separate any precipitated salt. After separation of precipitated salt, such a solution may contain about 29% of'sodium sodium chloride, 1.5% of sodium hydroxide and 62% of water. This solution may then be employed in the treat-' ment of calcium hypochlorite products in accordance with the present invention. If it is desired to avoid the addition of salt and caus tic alkali to the calcium hypochlorite product during treatment, a solution of sodium hypochlorite such as that just described may be cooled to freeze out 'sodium hypochlorite pentahydrate which can be filtered from the solution and employed in treatment of the calcium hypochlorite product. In carrying out the invention, the amount of calcium chloride in the calcium hypochlorite product is first determined and an amount of alkali hypochlorite approximately equivalent chemically to this calcium chloride is then employed in the treatment.

The invention will be illustrated by the folowing example: 47 pounds of sodium hypochlorite and 7 3 pounds of water are added to 500 pounds of a filter cake containing about 50.1% of calcium hypochlorite, 6.9% of calcium chloride, 5.7% of calcium hydroxide, 0.3% of sodium chloride and 37% of water and the mixture is thoroughly stirred and dried Without pressing. The resulting product contains less than-0.5% of calcium chloride.

e claim: 7 An improvement in eliminating calcium chloride from calcium hypochlorite products containing thesame which comprises treating the calcium hypochlorite product containing calcium chloride with an added alkali hypochlorite.

2. An improvement in eliminating calcium chloride from calcium hy rochlorite products containing the same whic comprises treating the calcium hypochlorite product containing out the invention.

Calcium chloride with added sodium hypochlorite added in amount approximately chlorite. n equivalent to the amount of calcium chloride 3. An improvement in:'eliminatingflpalcipresent in the product.

um chloride from caliumhypbchlorite prod- In testimony whereof we aflix our signa- 5 ucts containing the same which comprises tures.

treating the calcium hypochlorite product ANTHONY GEORGE.

containingcalciumchloride withalkali hypo- ROBERT MAGMULLIN." 

